This invention relates generally to electronic components and more particularly concerns low profile surface mountable electronic components having strengthened structures for absorbing forces attributable to mechanical shock.
The electronics industry is continually called upon to make products smaller and more powerful. Applications such as mobile phones, portable computers, computer accessories, hand-held electronics, etc., create a large demand for smaller electronic components. These applications further drive technology to research new areas and ideas with respect to miniaturizing electronics. Often times, applications specifically require xe2x80x9clow profilexe2x80x9d components due to constraints in height and width. Unfortunately, the technology is often limited due to the inability to make certain components smaller, faster, or more powerful. Nowhere can this be seen more than in the struggle to manufacture smaller electronic circuits.
Originally, components were mounted on a printed circuit board (PCB) by inserting the leads of the component through the PCB and soldering them to solder pads on the opposite side of the PCB, (called through-hole technology). This technique left half of the PCB unpopulated because one side had to be reserved for solder pads and solder. Therefore, in order to fit more components in a particular circuit, the PCBs were made larger, or additional PCBs were required. Many times, however, these options were not available due to constraints in size for the PCBs
The solution to this problem came in the form of Surface-Mount Devices (SMD), or Surface-Mount Technology. SMDs allow electrical components to be mounted on one side of a PCB, (i.e., without having the leads inserted through-holes). An SMD device has small metalized pads (solder pads or leads) connected to its body, which correspond to solder pads or lands placed on the surface of the PCB. Typically the PCB is run through a solder-paste machine (or screen printer), which puts a small amount of solder on the solder pads on the PCB. Next, a glue dot is inserted on the PCB where the component is to rest. Then, the component is placed on the PCB (held by the glue dot), and the PCB is sent through a re-flow oven to heat the solder paste and solder the component leads to the PCB solder pads. The primary advantage to this technique is that both sides of the PCB can now be populated by electronic components. Meaning one PCB today can hold an amount of electrical components equal to two PCBs in the past.
As a result of this advancement in technology, the current electronic circuits are mainly limited by the size of components used on the PCB. Meaning, if the electronic components are made smaller, the circuits are smaller as well. Unfortunately, there are some electronic components that can simply not be produced any smaller than they currently are. Usually this is because the desired parameters for the component cannot be achieved when using smaller parts and/or because the desired mechanical strength of the component cannot be met. A good example of this is inductive components. Inductive components are often used in stepper motors, transformers, servos, relays, inductors, antennas, etc. Typical applications requiring such components include radio frequency (RF), switching power supplies, converters, data communications, processor/controller circuits, signal conditioning circuits, biasing oscillators, DC-DC converters, DC-AC converters, chokes, IC investors, filters, etc. Certain parameters of these components are affected by the size of parts used. For instance, in inductors, wire gauge determines both the DC resistance and the current carrying ability of the component.
Furthermore, some electronic components cannot be manufactured in smaller forms because the smaller components simply cannot withstand the mechanical stresses and forces that such components are exposed to during testing or use. For example, certain materials used to manufacture smaller electronic components are often more brittle than other materials and are thus less able to withstand the mechanical forces exerted on the component during drop tests or normal use of the component. One example of this involves the materials used to manufacture the low profile antennas used in key fobs (or transmitters of keyless entry systems), which are often so brittle that they cannot withstand standard drop tests or certain drops which occur during typical usage of the device.
Moreover, some materials used to manufacture smaller electronics have temperature coefficient mismatches with the other portions of the component and/or the PCB which prevent them from being used in certain applications. For example, if some of the materials used to manufacture the transformers used for liquid crystal display (LCD) backlighting do not have closely matching temperature coefficients, one material may expand/contract during temperature changes faster or more than another material causing the connection between these materials to break. Such conditions cause component failures when the component is tested at temperature or used in elevated temperature conditions.
Accordingly, it has been determined that the need exists for an improved low profile electronic component which overcomes the aforementioned limitations and which further provides capabilities, features and functions, not available in current devices.
A low profile electronic component in accordance with the invention comprises a core having first and second ends with a main horizontal section extending therebetween and first and second supports for supporting the core and for absorbing forces applied to the component that are attributable to mechanical shock (e.g., impact forces, thermal stresses, etc.). Each support defines a receptacle for receiving one of the core""s first and second ends and provides a metalized pad with which the component can be electrically connected and mounted to a printed circuit board (PCB). Wire is wound about at least a portion of the main horizontal section of the core and the ends of the wire are connected to the metalized pads of the supports. The combination of supports and core allow the electronic component to withstand greater forces than if the component was made by simply using one solid portion.
In one embodiment, the electronic component comprises an antenna having a wire wound about a majority of the main horizontal section of the core. One end of the wire is electrically connected to a metalized pad located on one of the supports and the other end of the wire is electrically connected to a metalized pad located on the other support. A top portion may also be provided with the component so that it can be picked up using industry standard component placement equipment. This top portion can comprise a simple flattened rectangular surface connecting the supports or, as in the embodiment shown in the attached drawing figures, can comprise a generally flat top surface with outer sidewalls extending downward therefrom for covering at least a portion of the wire wound core.
In another embodiment, the electronic component comprises a transformer wherein the core comprises a sleeve within which an insert is disposed. The sleeve has first and second ends with a main horizontal section extending therebetween and at least one raised portion located about the main horizontal section of the sleeve for separating the sleeve into a first portion and a second portion. In the preferred form of this embodiment, the first and second ends of the sleeve are capable of being inserted into the receptacles of the supports and each support has at least two metalized pads. A first wire is wound around the first portion of the sleeve and has the ends of the wire connected to the metalized pads of one support (e.g., one end connected to one of the metalized pads of the first support and a second end connected to another one of the metalized pads on the first support). A second wire is then wound around the second portion of the sleeve and has the ends of the wire connected to the metalized pads of the other support.
A top portion may also be provided with the transformer component so that it can be picked up using industry standard component placement equipment. This top portion can comprise a generally flat top surface made from an acrylic or, as in a preferred embodiment, may comprise a magnetic material such as ferrite in order to enhance the performance of the electronic component. In alternate forms, the top portion may further comprise a generally flat top surface with outer sidewalls extending downward therefrom for covering at least a portion of the wire wound core, as discussed above.